Abutment and Orthodontics for Endurance of Dental Crowns

The split-increment horizontal placement (SHP) is the popular technique being used, along with other therapeutic modus operandi. As more than adequate, SHP methods are being enhanced in barricade cavities for reducing the shrinkage stress that were generated during light polymerization. Such stress, if released unrestrained, may redress within the composite, tooth or at the adhesive contact .

OPINION OF TEACHERS BY SPECIALTY “DENTAL TECHNICIAN“ FOR THE CONTINUING POSTGRADUATE TRAINING OF DENTAL TECHNICIANS IN BULGARIA

Postgraduate training of dental technicians is their right and obligation, to meet the expectations of patients and dentists in the provision of health care. On May 31, 2019, the Bulgarian Association of Dental Technicians was established. It is still unable to organize its activities in the direction - organization and control of postgraduate education. Our purpose is to find out if teachers are willing to participate in continuing education for practicing dental technicians, the directions in which they have the opportunity to do this and who should organize it. To achieve this purpose we used the following methods: study of literature sources, documents, sociologically, graphic and descriptive analysis to present the results. We found that, according to a large part, continuing education should be organized by Bulgarian Association of Dental Technicians, the second place is assigned to Bulgarian Association of Dental Technicians jointly with the colleges, and the third place is represented by the manufacturing companies of materials and devices. together with prominent specialists from the practice. Most of them are ready to participate in the postgraduate training of dental technicians, with the predominance of the respondents ready to organize courses in the field of modern methods and means for restoration of the defects of the dental crowns and dental rows with non-removable dental prosthetic structures. A small part of the teachers (27,78%) offer other additional courses, which will help practicing dental technicians: for development and management of practice; in the mentoring process; to create a publishing activity.

Dentist’s Perspective Regarding Usage of Different Fixed Prosthesis Removal Systems in Islamabad and Rawalpindi

Background: Crowns and multi-unit fixed partial dentures have a limited lifetime. They fail for a number of reasons. The removal of provisional crowns and bridges is generally simple, however for permanent crowns, it becomes more challenging. Careful removal of FPD can help a dentist simplify a resto or endo procedure. The aim of this article was to analyze the different methods available for the removal of crowns and bridges and their awareness among dental practitioners Study Design & location: This was a cross-sectional study based on a questionnaire. The questionnaire was filled by a total of 250 general and specialist dentists who were practicing in various individual and group-based dental practices as well as private and government setups of Islamabad and Rawalpindi. Methodology: The questionnaire comprised a total of 13 questions to find out dentists' views about the usage of different system’s available for dental crowns and FPD removal. Participants were selected by random sampling. The results were then analyzed using SPSS version 23. Frequencies, percentages of different variables used in the study were calculated to identify the co-relation among different attributes. P-value of less than or equal to 0.05 was considered statistically significant. Results: The study reflected that out of those who answered, 247 dental professionals (98.5 %) preferred using hemostats or Morrell sliding hammer or a combination of both as they offered better control of force. A small percentage (approx 2%) of dentists used diamond or carbide burs as their first preference to trim off old crowns. Clinicians rarely used laser due to its high cost and less availability and its effectiveness primarily related to Porcelain jacket/ Zirconium crowns. Conclusion: It was concluded from this study that the majority of dentists preferred Morrell type crown remover with sliding hammer due to its ease of availability, universal acceptance, simple to use and because as it offered better control of force as opposed to spring-lock type Keywords: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure.

Effect of Printing Layer Thickness on the Trueness and Margin Quality of 3D-Printed Interim Dental Crowns

The information in the literature on the effect of printing layer thickness on interim 3D-printed crowns is limited. In the present study, the effect of layer thickness on the trueness and margin quality of 3D-printed composite resin crowns was investigated and compared with milled crowns. The crowns were printed in 3 different layer thicknesses (20, 50, and 100 μm) by using a hybrid resin based on acrylic esters with inorganic microfillers or milled from polymethylmethacrylate (PMMA) discs and digitized with an intraoral scanner (test scans). The compare tool of the 3D analysis software was used to superimpose the test scans and the computer-aided design file by using the manual alignment tool and to virtually separate the surfaces. Deviations at different surfaces on crowns were calculated by using root mean square (RMS). Margin quality of crowns was examined under a stereomicroscope and graded. The data were evaluated with one-way ANOVA and Tukey HSD tests. The layer thickness affected the trueness and margin quality of 3D-printed interim crowns. Milled crowns had higher trueness on intaglio and intaglio occlusal surfaces than 100 μm-layer thickness crowns. Milled crowns had the highest margin quality, while 20 μm and 100 μm layer thickness printed crowns had the lowest. The quality varied depending on the location of the margin.

Al2O3 Preforms Infiltrated with Poly(methyl methacrylate) for Dental Prosthesis Manufacturing

The combination of biocompatible polymers and ceramics shows great promise in the development of composites with suitable mechanical properties for dental applications. In an attempt to further expand this research line, Al2O3 commercial powders (Vitro-ceram, Alglass, In-ceram) were sintered at 1400 °C for 2 h and infiltrated with poly(methyl methacrylate) for potential use in dental prostheses. The infiltration was performed using a homemade apparatus under a pressure of 7 bar for 6 and 12 h. The microstructure (studied using a scanning electron microscope), Archimedes density, 3-point bending flexural strength and Vickers hardness of the prepared composites were assessed and quantitatively compared. In general, microstructural analyses showed ceramic- and polymer-based interpenetrating network in all materials. The preforms infiltrated for 12 h showed superior properties; among them, the Vitro-ceram-based composite also demonstrated a near-zero open porosity and optimum mechanical characteristics. Specifically, its density, strength and hardness were 2.6 ± 0.07 g/cm3, 119.3 ± 5.0 MPa and 1055.1 ± 111.0 HV, respectively, passing the acceptance criteria of ISO 6872 and making it suitable for consideration as a metal-free structure for dental crowns and fixed partial prostheses until three anterior units.

Comparison of Intaglio Surface Trueness of Interim Dental Crowns Fabricated with SLA 3D Printing, DLP 3D Printing, and Milling Technologies

This study aimed to evaluate the intaglio surface trueness of interim dental crowns fabricated with three 3-dimensional (3D) printing and milling technologies. Dental crown was designated and assigned as a computer-aided design (CAD) reference model (CRM). Interim dental crowns were fabricated based on CRM using two types of 3D printer technologies (stereolithography apparatus and digital light processing) and one type of milling machine (n = 15 per technology). The fabricated interim dental crowns were obtained via 3D modeling of the intaglio surface using a laboratory scanner and designated as CAD test models (CTMs). The alignment and 3D comparison of CRM and CTM were performed based on the intaglio surface using a 3D inspection software program (Geomagic Control X). Statistical analysis was validated using one-way analysis of variance and Tukey HSD test (α = 0.05). There were significant differences in intaglio surface trueness between the three different fabrication technologies, and high trueness values were observed in the milling group (p < 0.05). In the milling group, there was a significant difference in trueness according to the location of the intaglio surface (p < 0.001). In the manufacturing process of interim dental crowns, 3D printing technologies showed superior and uniform manufacturing accuracy than milling technology.

Celiac disease: non-carious lesions of the teeth

The high prevalence of non-carious manifestations in patients with celiac disease is described by numerous authors, who are considered as a diagnostic key to atypical forms of celiac disease. The manifestations closely associated with celiac disease include: defects in tooth enamel, pathological tooth abrasion, as a violation of the mineralization of dental crowns, and morphofunctional defects in the hard tissues of the teeth.Materials and methods. We examined 45 patients aged 23 to 36 years with a diagnosis of celiac disease, established on the basis of the results of clinical anamnestic, genetic, instrumental studies, morphological study of a biopsy specimen of the intestinal mucosa.Result. Examination of the dentition of the patients showed that 100% of the examined had pathological abrasion of tooth enamel. Crowded teeth were found in 32 patients. Partial symmetric congenital adentia was diagnosed in 5 patients.Conclusion. The revealed dentoalveolar anomalies can be attributed to oral manifestations of celiac disease, which is a diagnostic criterion for suspected disease.